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    Re: Halley's lunar knowledge.
    From: Fred Hebard
    Date: 2007 Nov 26, 17:44 -0500

    
    On Nov 25, 2007, at 11:20 PM, Michael Daly wrote:
    
    >
    > George Huxtable wrote:
    >> and for some reason he pointed to an anonymous contemporary review of
    >> Halley's Southern-stars catalogue. I don't understand its
    >> relevance, but am
    >> grateful for that mention, as I had not seen it before.
    >
    > You said you hadn't read Phil. Trans.vol. 12, no. 141 (1678), 1032-4.
    > Well, that's it.  An anonymous review.
    >
    >
    >> Are those what Daly appears now to dismiss as "raw data"?
    >
    > Of course they are raw data.  Halley did not go into his friendly,
    > neighbourhood navigator's supply shop and buy a printed copy of the
    > lunar information telling him when a particular star would be occulted
    > _in_the_future_ by the moon.  He had data that specified the position
    > information on the moon - in the past.  That's raw data.  He has to
    > use
    > it along with a model of lunar motion to produce the information he
    > needs.
    >
    >
    > Mike
    
    
    Mike,
    
    You appear to have missed the point of both George and Frank Reed's
    post that Halley did not need a model; it could be done empirically
    knowing that the moon was back in the same spot after 18 years x days
    later, based upon data collected beforehand.
    
    Fred
    
    
    
    
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